Konami rom logo screen out of sync, otherwise all ok?!

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By Pentarou

Master (137)

Pentarou's picture

05-10-2018, 19:57

Remove R102, R103, R104; replace R101 with a 120 Ohm: connect the base of transistor Q15 (2SC2S03 which was connected to R102/R103/R104) to pin #6 of the VDP via a 1K Ohm resistor. Replace LF67 (EMI filter) with a 470uF capacitor (plus side towards the base *** of the transistor Q15).

***it says base but in the schematic it looks like the emitter, or better still, the (68~75 Ohm) resistor connected to the emitter.

If your friend gets his livelihood from electronic work, the schematic alone should be enough Big smile

BTW. I also had the DIN version of the 8235 and had shaky images. I bypassed the U13 Gate and the CVBS circuit and replaced the DIN part of the SYNC output with the FR version. Now it looks good but I wonder if Jipe's mod may be better Cool
I also thought that the stock VG8235 had bad colors, really lacking compared to the Sony HBF700...
So I replaced all the output transistors with a THS73* based amplifier. Now colors look really good! Tongue

By olliraa

Champion (293)

olliraa's picture

06-10-2018, 13:37

Quote:

Remove R102, R103, R104; replace R101 with a 120 Ohm: connect the base of transistor Q15 (2SC2S03 which was connected to R102/R103/R104) to pin #6 of the VDP via a 1K Ohm resistor. Replace LF67 (EMI filter) with a 470uF capacitor (plus side towards the base *** of the transistor Q15).

***it says base but in the schematic it looks like the emitter, or better still, the (68~75 Ohm) resistor connected to the emitter.

Ok, thanks Smile I'll take the Philips into pieces once again. Doh :/ I guess this time I'll have to buy my friend two bottles of wine instead of the standard one, because my the deflection board of my BVM20F1E also seems to need some "cap lovin'" Big smile

I'll report here as the thing progresses. Might take a week or two though.

Thank you all for the tips and help Running Naked in a Field of Flowers

By olliraa

Champion (293)

olliraa's picture

06-10-2018, 20:06

Removed the post. Sorry, found it.

By olliraa

Champion (293)

olliraa's picture

12-10-2018, 07:45

This is just awesome Smile My friend did the fixes and now I have a perfectly working MSX2+ Big smile Big smile White background is perfect!

Thank you all for your kind help on this. Could have not pulled this together myself. Special thanks for Jipe for the instructions regarding the sync on Philipses Big smile

Now excuse me, i'll Running Naked in a Field of Flowers Running Naked in a Field of Flowers Running Naked in a Field of Flowers Running Naked in a Field of Flowers Running Naked in a Field of Flowers Running Naked in a Field of Flowers Running Naked in a Field of Flowers

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